FACTORS AFFECTING THE VIABILITY OF AIR-BORNE BACTERIA: I. BACTERIA AEROSOLIZED FROM DISTILLED WATER

Abstract

The death of bacterial cells aerosolized from distilled water suspensions has been studied over a 5-hour period. It was found that death occurred in two stages, a rapid initial kill taking place within the first second and a subsequent slower death. First-order kinetics only applied to this secondary death at low relative humidity ranges, and this is taken to indicate that at least two reactions are responsible for viable decay. The death rates of the air-borne cells have been correlated with a mathematical function of both temperature and humidity. Activation energies associated with aerosol death have been found to increase from 4000 cal/mole to 12,000 cal/mole as the cells age in air. It is suggested that the death of the cell results from the movement of water molecules in and out of the cell, in an equilibrium system, resulting in a collapse of the natural structure of cellular protein.